5 HP Briggs

Have A 5 Hp Briggs on my troy bilt tiller and I need to know how to set the gas and air valve Right now I have to really choke it to start it and leave the choke on until it is fully warmed up or it will die when I engage the drive, so if someone could tell me how much to back out from fully screwed in it would be most helpful thanks to all Ken
 
Not sure which carb you have, if it has idle and main jet adjustment, or just idle mix adjustment.

Start with the idle mix screw. That will be the one near the throttle plate. Gently turn it in until it just bottoms, then back it out 1 1/2 turns.

If it has a main adjustment screw, turn it in and count the turns until it bottoms, then return it to where it was. (Do this because it was successfully running at this setting.) Remember, turning either screw in will lean the mixture, out will make it richer.

With the air filter in place and clean, the engine up to operating temp, and the engine idling at a slow speed, turn the mix screw in until the engine starts to stumble, then back it out so it runs smooth, then back it out about another 1/8 turn. Try rapidly accelerating the engine from idle. It should rev quickly, without hesitation. A puff of dark smoke is good.

If it hesitates or dies, back out the main adjustment about 1/4 turn and try again. Keep adjusting them until it accelerates without hesitation and runs at full governed speed without black smoke.

At this point it should restart warm without choke, and it should take sudden throttle without hesitation, and should run full power, under load, without black smoke or stumbling.
 
If you can't get eng to run correctly with settings suggested by steve & mngb and eng has a pulse jet carb you may have a fuel pump diaphram that needs replacement due to age hardening or damaged due to ethanol content of gas,the pulse jet is/was made in two versions,on one version pump diaphram is located between tank & carb,other version carb has a four bolt cover on outboard side of carb body & diaphram under cover.
 
Oh ya, I changed quite a few of those pulsa jet diaphrams! Don't forget to tell him how to "true" the tank where it warps a little. I use a nice new flat file to gently surface the top part of the bowl and tank area. Fixed most all of them. Installed a lot of the Magnatons onto those engines if they still had points. What a little miracle in a box! Jeffcat
 
If it is necessary to replace pump diaphram take the extra time to check screen filters on end of pickup tube(s) that extend into tank from carb body,screen(s) may be dirty/gummed up.
 
(quoted from post at 02:35:52 05/25/14) If it is necessary to replace pump diaphram take the extra time to check screen filters on end of pickup tube(s) that extend into tank from carb body,screen(s) may be dirty/gummed up.

Yes indeed check the screens. I recently placed a generator into service after many years of sitting. It was an auction purchase with a 5HP B&S - the fuel was brown/yellow and smelled up the entire shop. After filling with fresh E-10 the engine started and ran well.

Two days later I went to use the generator and it would only run on choke. I removed the carb/fuel tank for disassembly. All looked well to my surprize, except the screen below the main jet was coated with a soft gummy film. I assembled everything without the screen and the engine then ran fine without choke after warm up.

I concluded(?) the fresh fuel soften/swelled the varnish deposit on the fine screen enough to restrict flow to the main jet. I had also noticed this before with a tiller that used the long dip tube and small screen in the end.

Note - I am not recommending use without the screens. I had actually cleaned the screen and found it in on the work bench the next day. Just decided not to take every thing apart again.
 
If you file tanks fairly often you might want to consider keeping several briggs pn391413 repair kits on hand which have been avail since the 70's for repairing warped tank or several of the stens pn525758 repair kits which are at least 1/2 the cost of briggs kit,either one will save a lot of time/flustration.
 

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